In general you want to be at or very close to the 25% gear Haste cap (26% Haste when you add up the % Haste values on the gear itself), and then add in Dual Wield gear when possible. Because of the 10% Dual Wield on the DNC Empyrean body, you'll be hard pressed to replace that in a TP set unless you're also getting external Haste buffs and are hitting the total Attack speed cap already. Twilight Belt will end up being better than Nusku's Sash (for DNC anyway, it has its place for THF and NIN if you don't have Patentia) and you'll want to use Charis over Love Torque. In Adoulin areas, with Ionis and the +% Haste from it, you can basically go with this setup as far as Haste/Dual Wield and should be fine.

That gives me just short of capped gear Haste in non/Adoulin areas with 15% Dual Wield in gear as well. It can obviously be better, what with Iuitl augments and all, but that set is generally going to be one of your best options.